Kahjin’s Weblog


Posted in 未分類 by kahjin on 4月 3, 2008


The greater the amount of the unbalanced force, the more rapidly a given object’s speed or direction of motion changes; the more massive an object is, the less rapidly its speed or direction changes in response to any given force. And whenever some thing A exerts a force on some thing B, B exerts an equally strong force back on A. For example, iron nail A pulls on magnet B with the same amount of force as magnet B pulls on iron nail A—but in the opposite direction. In most familiar situations, friction between surfaces brings forces into play that complicate the description of motion, although the basic principles still apply.




Some complicated motions can be described most conveniently not in terms of forces directly but in summary descriptions of the pattern of motion, such as vibrations and waves. Vibration involves parts of a system moving back and forth in much the same place, so the motion can be summarized by how frequently it is repeated and by how far a particle is displaced during a cycle. Another summary characteristic is the rate at which the vibration, when left to itself, dies down as its energy dissipates.





Vibrations may set up a traveling disturbance that spreads away from its source. Examples of such disturbances are sound, light, and earthquakes, which show some behavior very like that of familiar surface waves on water—changing direction at boundaries between media, diffracting around corners, and mutually interfering with one another in predictable ways. We therefore speak of sound waves, light waves, and so on, and the mathematics of wave behavior is useful in describing all these phenomena. Wave behavior can also be described in terms of how fast the disturbance propagates, and in terms of the distance between successive peaks of the disturbance (the wavelength).


1*:travelingを”横方向”としたのはwikipediaのwaveの項目にtraveling wave とstanding waveとあったので。standingって縦っぽいから。

2*:propagateは伝播するというようりも、語源の訳にあるtravel throughを意味として使用した




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  1. hermes リボン バッグ said, on 9月 5, 2013 at 4:07 am

    hermes 財布 一覧



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